1. Field of the Invention
This invention relates to a simultaneous filling blow molding method and apparatus, and more particularly to a simultaneous filling blow molding method and apparatus which prevents pollution to a molded article arising from invasion of foreign substances and eliminates germs from the molded article.
2. Description of the Related Art
When a medicine or food is filled into a hollow article molded by a blow molding apparatus, prevention of pollution to and elimination of germs from the inside of the hollow article must be achieved. One of conventionally known blow molding methods and apparatus of the type mentioned is disclosed, for example, in Japanese Patent Publication Application No. Heisei 7-35089 and is described below with reference to FIGS. 1 to 4.
As shown in FIG. 1, a parison molding nozzle 71 which opens downwardly is provided on a cross head 70 attached to an end portion of an extruder (not shown). A metallic mold 74 held on a movable frame 72 by means of a holding plate 73 is opened and closed by a driving cylinder (not shown) incorporated in the movable frame 72. The movable frame 72 is supported on a frame 76 by means of a pair of link arms 75. A connection block 77 is provided projectingly on the rear face of the movable frame 72, and a driving cylinder 78 is disposed between the connection block 77 and the frame 76. As the driving cylinder 78 is expanded and contracted, the movable frame 72 can be moved back and forth between a parison receiving position (solid line in FIG. 1) in which the metallic mold 74 is positioned just below the cross head 70 and a blow position (imaginary line in FIG. 1) in which the metal mold 74 is positioned just below blow cylinders 79 which will be hereinafter described.
As seen from FIG. 2, each of the blow cylinders 79 is formed from a fixed casing 80 and a movable rod 81, and an air mandrel 82 is connected to an end of the rod 81. The blow cylinder 79 can drive the rod 81 and the air mandrel 82 upwardly and downwardly by an air pressure or a hydraulic pressure, and the air mandrel 82 can jet clean air from an end thereof when an air source is connected to the air mandrel 82. An accommodating case 84 is mounted on the lower face of a horizontal base 83 to which the blow cylinders 79 are attached. The accommodating case 84 has a fully enclosed structure except that it has, in a bottom wall thereof, round holes 84a for passing the rods 81 and the air mandrels 82 therethrough. Air pipes 87 for supplying clean air are accommodated in the accommodating case 84, and the accommodating case 84 is normally filled with clean air. It is to be noted that the accommodating case 84 can accommodate the entire of the air mandrels 82 when the air mandrels 82 are moved upwardly.
As shown in FIG. 3, seal dies 85 are provided between the lower face of the accommodating case 84 and the upper face of the metallic mold 74 and are opened or closed by a cylinder not shown to seal an upper end portion of a parison.
Operation of the blow molding apparatus is described below.
When parisons 86 are extruded to a fixed length from the parison molding nozzles 71, the metallic mold 74 is closed, and the parisons 86 are cut by cutter apparatus not shown provided on the cross head 70. Then, the movable frame 72 is moved to the blow position. Then, if the blow cylinders 79 are expanded there, then the ends of the blow cylinders 79 are inserted into the parisons 86 in the metallic mold 74 (imaginary line in FIG. 2), and therefore, the parisons 86 can be blow molded by blowing clean air into the parisons 86. It is to be noted that, as seen in FIG. 3, before the air mandrel 82 is moved upwardly, the seal dies 85 stand by at a position a little above the level of the upper face of the metallic mold 74 at which they hold the air mandrels 82 therebetween, and if the air mandrels 82 are moved upwardly, then the seal dies 85 are closed to mold and seal upper end portions of the parisons 86. Thereafter, if the metallic mold 74 is opened and the seal dies 85 are opened, then such hollow articles each having such a cap element as shown in FIG. 4 are discharged downwardly. By thereafter repeating similar operations, hollow articles can be produced successively. In the operations described above, the air mandrels 82 are cleaned by clean air supplied from the air pipes 87 while they remain accommodated in the accommodating case 84.
Since the blow molding method and apparatus described in the prior art is constructed in such a manner as described above, it has the following disadvantages.
(a) After a hollow article wherein an opening of a vessel body is temporarily closed up with a cap element is molded, it is transported to a filling apparatus provided separately. Then, by the filling apparatus, only the outside of the hollow article is sterilized and the upper end is unsealed, and then filling and sealing are performed. Where the blow molding apparatus and the filling apparatus are formed separately from each other in this manner, temporary sealing, unsealing, filling and capping steps are required to produce a filled up hollow article. Consequently, the process is complicated, and a sterilizing operation must be performed in each of the steps.
(b) In a process wherein the metallic mold is moved back and forth in an inclined direction between the parison receiving position just below the cross head and the blow position in which the metallic mold is positioned just below the blow cylinder, there is the possibility that some foreign substances may be admitted into the inside of the parison.
(c) Since the ends of the air mandrels are inserted into parisons in the metallic mold and air from the air source is blown into the parisons to blow mold the parisons, there is the possibility that some foreign substances may be admitted into the insides of the parisons from the air source or a pipe system.
(d) The risk that, if hydraulic operating fluid leaks from the driving cylinders, hydraulic units or the pipe system used for the movement of the metallic mold, for the opening and closing of the metallic mold or for the upward and downward movement of the air mandrels, then hollow articles may be polluted or mist of the hydraulic operating fluid may enter the insides of the parisons or otherwise the inner faces of the hollow articles may be polluted is always present. Particularly, if hydraulic operating fluid leaks from the driving cylinders for the air mandrels, then since hollow articles are present below the driving cylinders, there is the possibility that the hydraulic operating fluid may enter the hollow articles via the air mandrels.
(e) Where the cutter of each of the cutter apparatus for cutting a parison is an electrothermal hot cutter, there is the possibility that the parison (plastic) may be melted by the heated cutter until volatile gas or fine carbonized particles of the plastic are scattered into the air and the inside of the parison is polluted with them.
(f) Since a filling cylinder which sucks and discharges a fixed amount of liquid is usually used for filling of liquid by a filling apparatus, the liquid is likely to stay in the inside of the filling cylinder and so forth and cleaning or sterilization of it cannot be performed readily.